Bacteroides

What does this bacterium look like? 

Bacteroides is a rod of approximately 1 to 12 micrometers long. This bacterium can become very large when compared to other bacteria, but it is not that large when you know that 1,000 micrometers fit into one millimeter. In Greek, “bakterion” means “small rod” and the suffix “-oïdes” means “shape”, “form” or “resembling”. The name of this bacterium therefore literally refers to its typical rod shape.

What does science already know about this bacterium?

Bacteroides does not tolerate oxygen well and is therefore difficult to cultivate in the lab. Nevertheless, scientists have already discovered quite a lot about this bacterium. Bacteroides sometimes accounts for more than a quarter of the entire gut microbiome, which is what makes research into this bacterium so useful.

There are several known species, such as Bacteroides fragilis and Bacteroides thetaiotaomicron. Bacteroides fragilis is probably the best-known species and has been extensively researched.

The amount and composition of Bacteroides in the gut varies from person to person. So it is quite possible that you have more or less Bacteroides in your gut than your mum, neighbor, good friend, and so on. What else? Different species and strains might be there. There can be various reasons for this variation, such as different dietary habits. Altogether, it remains somewhat of a mystery, reflected in an important question: which species does what in your gut?

We already know that Bacteroides has an average genome size between 5 and 7 million base pairs with more than 5,000 genes. This means that this bacterium can produce more than 5,000 different substances. By comparison, our favorite Lactobacillus bacteria have far fewer genes. Why? Well, the gut is an extremely dynamic environment. Sometimes there is a large amount of food, sometimes almost nothing. In addition, there is fierce competition between various bacterial species. Bacteroides must therefore be flexible in order to survive, and this is reflected in a large number of genes.

What is this bacterium doing in my gut?

Bacteroides is an important inhabitant of your gut. It is a hard worker that loves food residues that you cannot digest yourself, such as fiber from fruit and vegetables. When Bacteroides gets to work, it converts those food residues into useful substances that benefit your intestinal wall (or intestinal lining). We call these useful substances short-chain fatty acids. They provide energy to your intestinal cells and thus contribute to a healthy intestinal wall.

Did you know that vitamin B2 or riboflavin also plays an important role here? Bacteroides can produce riboflavin itself and uses it as a building block for enzymes (these are proteins with a specific function) that help break down complex carbohydrates. In addition, riboflavin is released into the intestinal environment, where it can be shared with other bacteria and your own body. This vitamin is even involved in activating a certain type of immune cells (also known as MAIT cells) that train your immune system. And that’s a good thing, because it teaches your body how to distinguish between “friend” and “foe”. This means that only the real enemies are tackled while the beneficial bacteria are left alone. In this way, Bacteroides helps to maintain peace in your gut. In our VIAB2L study, the Isala daughter study with a central focus on vitamin B2, we want to investigate whether we can further enhance these effects by supplementing riboflavin itself or lactobacilli that produce riboflavin!

In short, Bacteroides is working hard behind the scenes to keep your digestion running smoothly and your immune system in balance!